Astigmatism is an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of the cornea or lens. The two types of astigmatism are regular and irregular. Irregular astigmatism is often caused by a corneal scar, ocuar laceration, corneal ectatic disease, or scattering in the crystalline lens, and cannot be corrected by standard spectacle lenses, but can be corrected or neutralized by certain contact lenses. The more common regular astigmatism can be corrected by eyeglasses or toric lenses. The refractive error of the astigmatic eye stems from a difference in degree of curvature refraction of the two different meridians. For example, the image may be clearly focused on the retina in the horizontal plane, but not in the vertical plane. Astigmatism causes difficulties in seeing fine detail resulting in blurred vision.